JSC2011-E-054076 (13 June 2011) --- NASA astronauts Sandy Magnus and Rex Walheim (mostly obscured), both STS-135 mission specialists, attired in training versions of their Extravehicular Mobility Unit (EMU) spacesuits, are about to be submerged in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Divers are in the water to assist Magnus and Walheim in their rehearsal. Photo credit: NASA